/*

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 /*

  * This file is available under and governed by the GNU General Public

  * License version 2 only, as published by the Free Software Foundation.

  * However, the following notice accompanied the original version of this

  * file:

  *

  * Written by Doug Lea and Josh Bloch with assistance from members of JCP

  * JSR-166 Expert Group and released to the public domain, as explained at

  * http://creativecommons.org/publicdomain/zero/1.0/

  */

 package java.util;

 /**

  * A {@link SortedMap} extended with navigation methods returning the

  * closest matches for given search targets. Methods

  * {@code lowerEntry}, {@code floorEntry}, {@code ceilingEntry},

  * and {@code higherEntry} return {@code Map.Entry} objects

  * associated with keys respectively less than, less than or equal,

  * greater than or equal, and greater than a given key, returning

  * {@code null} if there is no such key.  Similarly, methods

  * {@code lowerKey}, {@code floorKey}, {@code ceilingKey}, and

  * {@code higherKey} return only the associated keys. All of these

  * methods are designed for locating, not traversing entries.

  *

  * <p>A {@code NavigableMap} may be accessed and traversed in either

  * ascending or descending key order.  The {@code descendingMap}

  * method returns a view of the map with the senses of all relational

  * and directional methods inverted. The performance of ascending

  * operations and views is likely to be faster than that of descending

  * ones.  Methods {@code subMap}, {@code headMap},

  * and {@code tailMap} differ from the like-named {@code

  * SortedMap} methods in accepting additional arguments describing

  * whether lower and upper bounds are inclusive versus exclusive.

  * Submaps of any {@code NavigableMap} must implement the {@code

  * NavigableMap} interface.

  *

  * <p>This interface additionally defines methods {@code firstEntry},

  * {@code pollFirstEntry}, {@code lastEntry}, and

  * {@code pollLastEntry} that return and/or remove the least and

  * greatest mappings, if any exist, else returning {@code null}.

  *

  * <p>Implementations of entry-returning methods are expected to

  * return {@code Map.Entry} pairs representing snapshots of mappings

  * at the time they were produced, and thus generally do <em>not</em>

  * support the optional {@code Entry.setValue} method. Note however

  * that it is possible to change mappings in the associated map using

  * method {@code put}.

  *

  * <p>Methods

  * {@link #subMap(Object, Object) subMap(K, K)},

  * {@link #headMap(Object) headMap(K)}, and

  * {@link #tailMap(Object) tailMap(K)}

  * are specified to return {@code SortedMap} to allow existing

  * implementations of {@code SortedMap} to be compatibly retrofitted to

  * implement {@code NavigableMap}, but extensions and implementations

  * of this interface are encouraged to override these methods to return

  * {@code NavigableMap}.  Similarly,

  * {@link #keySet()} can be overriden to return {@code NavigableSet}.

  *

  * <p>This interface is a member of the

  * <a href="{@docRoot}/../technotes/guides/collections/index.html">

  * Java Collections Framework</a>.

  *

  * @author Doug Lea

  * @author Josh Bloch

  * @param <K> the type of keys maintained by this map

  * @param <V> the type of mapped values

  * @since 1.6

  */

 public interface NavigableMap<K,V> extends SortedMap<K,V> {

     /**

      * Returns a key-value mapping associated with the greatest key

      * strictly less than the given key, or {@code null} if there is

      * no such key.

      *

      * @param key the key

      * @return an entry with the greatest key less than {@code key},

      *         or {@code null} if there is no such key

      * @throws ClassCastException if the specified key cannot be compared

      *         with the keys currently in the map

      * @throws NullPointerException if the specified key is null

      *         and this map does not permit null keys

      */

     Map.Entry<K,V> lowerEntry(K key);

     /**

      * Returns the greatest key strictly less than the given key, or

      * {@code null} if there is no such key.

      *

      * @param key the key

      * @return the greatest key less than {@code key},

      *         or {@code null} if there is no such key

      * @throws ClassCastException if the specified key cannot be compared

      *         with the keys currently in the map

      * @throws NullPointerException if the specified key is null

      *         and this map does not permit null keys

      */

     K lowerKey(K key);

     /**

      * Returns a key-value mapping associated with the greatest key

      * less than or equal to the given key, or {@code null} if there

      * is no such key.

      *

      * @param key the key

      * @return an entry with the greatest key less than or equal to

      *         {@code key}, or {@code null} if there is no such key

      * @throws ClassCastException if the specified key cannot be compared

      *         with the keys currently in the map

      * @throws NullPointerException if the specified key is null

      *         and this map does not permit null keys

      */

     Map.Entry<K,V> floorEntry(K key);

     /**

      * Returns the greatest key less than or equal to the given key,

      * or {@code null} if there is no such key.

      *

      * @param key the key

      * @return the greatest key less than or equal to {@code key},

      *         or {@code null} if there is no such key

      * @throws ClassCastException if the specified key cannot be compared

      *         with the keys currently in the map

      * @throws NullPointerException if the specified key is null

      *         and this map does not permit null keys

      */

     K floorKey(K key);

     /**

      * Returns a key-value mapping associated with the least key

      * greater than or equal to the given key, or {@code null} if

      * there is no such key.

      *

      * @param key the key

      * @return an entry with the least key greater than or equal to

      *         {@code key}, or {@code null} if there is no such key

      * @throws ClassCastException if the specified key cannot be compared

      *         with the keys currently in the map

      * @throws NullPointerException if the specified key is null

      *         and this map does not permit null keys

      */

     Map.Entry<K,V> ceilingEntry(K key);

     /**

      * Returns the least key greater than or equal to the given key,

      * or {@code null} if there is no such key.

      *

      * @param key the key

      * @return the least key greater than or equal to {@code key},

      *         or {@code null} if there is no such key

      * @throws ClassCastException if the specified key cannot be compared

      *         with the keys currently in the map

      * @throws NullPointerException if the specified key is null

      *         and this map does not permit null keys

      */

     K ceilingKey(K key);

     /**

      * Returns a key-value mapping associated with the least key

      * strictly greater than the given key, or {@code null} if there

      * is no such key.

      *

      * @param key the key

      * @return an entry with the least key greater than {@code key},

      *         or {@code null} if there is no such key

      * @throws ClassCastException if the specified key cannot be compared

      *         with the keys currently in the map

      * @throws NullPointerException if the specified key is null

      *         and this map does not permit null keys

      */

     Map.Entry<K,V> higherEntry(K key);

     /**

      * Returns the least key strictly greater than the given key, or

      * {@code null} if there is no such key.

      *

      * @param key the key

      * @return the least key greater than {@code key},

      *         or {@code null} if there is no such key

      * @throws ClassCastException if the specified key cannot be compared

      *         with the keys currently in the map

      * @throws NullPointerException if the specified key is null

      *         and this map does not permit null keys

      */

     K higherKey(K key);

     /**

      * Returns a key-value mapping associated with the least

      * key in this map, or {@code null} if the map is empty.

      *

      * @return an entry with the least key,

      *         or {@code null} if this map is empty

      */

     Map.Entry<K,V> firstEntry();

     /**

      * Returns a key-value mapping associated with the greatest

      * key in this map, or {@code null} if the map is empty.

      *

      * @return an entry with the greatest key,

      *         or {@code null} if this map is empty

      */

     Map.Entry<K,V> lastEntry();

     /**

      * Removes and returns a key-value mapping associated with

      * the least key in this map, or {@code null} if the map is empty.

      *

      * @return the removed first entry of this map,

      *         or {@code null} if this map is empty

      */

     Map.Entry<K,V> pollFirstEntry();

     /**

      * Removes and returns a key-value mapping associated with

      * the greatest key in this map, or {@code null} if the map is empty.

      *

      * @return the removed last entry of this map,

      *         or {@code null} if this map is empty

      */

     Map.Entry<K,V> pollLastEntry();

     /**

      * Returns a reverse order view of the mappings contained in this map.

      * The descending map is backed by this map, so changes to the map are

      * reflected in the descending map, and vice-versa.  If either map is

      * modified while an iteration over a collection view of either map

      * is in progress (except through the iterator's own {@code remove}

      * operation), the results of the iteration are undefined.

      *

      * <p>The returned map has an ordering equivalent to

      * <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>.

      * The expression {@code m.descendingMap().descendingMap()} returns a

      * view of {@code m} essentially equivalent to {@code m}.

      *

      * @return a reverse order view of this map

      */

     NavigableMap<K,V> descendingMap();

     /**

      * Returns a {@link NavigableSet} view of the keys contained in this map.

      * The set's iterator returns the keys in ascending order.

      * The set is backed by the map, so changes to the map are reflected in

      * the set, and vice-versa.  If the map is modified while an iteration

      * over the set is in progress (except through the iterator's own {@code

      * remove} operation), the results of the iteration are undefined.  The

      * set supports element removal, which removes the corresponding mapping

      * from the map, via the {@code Iterator.remove}, {@code Set.remove},

      * {@code removeAll}, {@code retainAll}, and {@code clear} operations.

      * It does not support the {@code add} or {@code addAll} operations.

      *

      * @return a navigable set view of the keys in this map

      */

     NavigableSet<K> navigableKeySet();

     /**

      * Returns a reverse order {@link NavigableSet} view of the keys contained in this map.

      * The set's iterator returns the keys in descending order.

      * The set is backed by the map, so changes to the map are reflected in

      * the set, and vice-versa.  If the map is modified while an iteration

      * over the set is in progress (except through the iterator's own {@code

      * remove} operation), the results of the iteration are undefined.  The

      * set supports element removal, which removes the corresponding mapping

      * from the map, via the {@code Iterator.remove}, {@code Set.remove},

      * {@code removeAll}, {@code retainAll}, and {@code clear} operations.

      * It does not support the {@code add} or {@code addAll} operations.

      *

      * @return a reverse order navigable set view of the keys in this map

      */

     NavigableSet<K> descendingKeySet();

     /**

      * Returns a view of the portion of this map whose keys range from

      * {@code fromKey} to {@code toKey}.  If {@code fromKey} and

      * {@code toKey} are equal, the returned map is empty unless

      * {@code fromInclusive} and {@code toInclusive} are both true.  The

      * returned map is backed by this map, so changes in the returned map are

      * reflected in this map, and vice-versa.  The returned map supports all

      * optional map operations that this map supports.

      *

      * <p>The returned map will throw an {@code IllegalArgumentException}

      * on an attempt to insert a key outside of its range, or to construct a

      * submap either of whose endpoints lie outside its range.

      *

      * @param fromKey low endpoint of the keys in the returned map

      * @param fromInclusive {@code true} if the low endpoint

      *        is to be included in the returned view

      * @param toKey high endpoint of the keys in the returned map

      * @param toInclusive {@code true} if the high endpoint

      *        is to be included in the returned view

      * @return a view of the portion of this map whose keys range from

      *         {@code fromKey} to {@code toKey}

      * @throws ClassCastException if {@code fromKey} and {@code toKey}

      *         cannot be compared to one another using this map's comparator

      *         (or, if the map has no comparator, using natural ordering).

      *         Implementations may, but are not required to, throw this

      *         exception if {@code fromKey} or {@code toKey}

      *         cannot be compared to keys currently in the map.

      * @throws NullPointerException if {@code fromKey} or {@code toKey}

      *         is null and this map does not permit null keys

      * @throws IllegalArgumentException if {@code fromKey} is greater than

      *         {@code toKey}; or if this map itself has a restricted

      *         range, and {@code fromKey} or {@code toKey} lies

      *         outside the bounds of the range

      */

     NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive,

                              K toKey,   boolean toInclusive);

     /**

      * Returns a view of the portion of this map whose keys are less than (or

      * equal to, if {@code inclusive} is true) {@code toKey}.  The returned

      * map is backed by this map, so changes in the returned map are reflected

      * in this map, and vice-versa.  The returned map supports all optional

      * map operations that this map supports.

      *

      * <p>The returned map will throw an {@code IllegalArgumentException}

      * on an attempt to insert a key outside its range.

      *

      * @param toKey high endpoint of the keys in the returned map

      * @param inclusive {@code true} if the high endpoint

      *        is to be included in the returned view

      * @return a view of the portion of this map whose keys are less than

      *         (or equal to, if {@code inclusive} is true) {@code toKey}

      * @throws ClassCastException if {@code toKey} is not compatible

      *         with this map's comparator (or, if the map has no comparator,

      *         if {@code toKey} does not implement {@link Comparable}).

      *         Implementations may, but are not required to, throw this

      *         exception if {@code toKey} cannot be compared to keys

      *         currently in the map.

      * @throws NullPointerException if {@code toKey} is null

      *         and this map does not permit null keys

      * @throws IllegalArgumentException if this map itself has a

      *         restricted range, and {@code toKey} lies outside the

      *         bounds of the range

      */

     NavigableMap<K,V> headMap(K toKey, boolean inclusive);

     /**

      * Returns a view of the portion of this map whose keys are greater than (or

      * equal to, if {@code inclusive} is true) {@code fromKey}.  The returned

      * map is backed by this map, so changes in the returned map are reflected

      * in this map, and vice-versa.  The returned map supports all optional

      * map operations that this map supports.

      *

      * <p>The returned map will throw an {@code IllegalArgumentException}

      * on an attempt to insert a key outside its range.

      *

      * @param fromKey low endpoint of the keys in the returned map

      * @param inclusive {@code true} if the low endpoint

      *        is to be included in the returned view

      * @return a view of the portion of this map whose keys are greater than

      *         (or equal to, if {@code inclusive} is true) {@code fromKey}

      * @throws ClassCastException if {@code fromKey} is not compatible

      *         with this map's comparator (or, if the map has no comparator,

      *         if {@code fromKey} does not implement {@link Comparable}).

      *         Implementations may, but are not required to, throw this

      *         exception if {@code fromKey} cannot be compared to keys

      *         currently in the map.

      * @throws NullPointerException if {@code fromKey} is null

      *         and this map does not permit null keys

      * @throws IllegalArgumentException if this map itself has a

      *         restricted range, and {@code fromKey} lies outside the

      *         bounds of the range

      */

     NavigableMap<K,V> tailMap(K fromKey, boolean inclusive);

     /**

      * {@inheritDoc}

      *

      * <p>Equivalent to {@code subMap(fromKey, true, toKey, false)}.

      *

      * @throws ClassCastException       {@inheritDoc}

      * @throws NullPointerException     {@inheritDoc}

      * @throws IllegalArgumentException {@inheritDoc}

      */

     SortedMap<K,V> subMap(K fromKey, K toKey);

     /**

      * {@inheritDoc}

      *

      * <p>Equivalent to {@code headMap(toKey, false)}.

      *

      * @throws ClassCastException       {@inheritDoc}

      * @throws NullPointerException     {@inheritDoc}

      * @throws IllegalArgumentException {@inheritDoc}

      */

     SortedMap<K,V> headMap(K toKey);

     /**

      * {@inheritDoc}

      *

      * <p>Equivalent to {@code tailMap(fromKey, true)}.

      *

      * @throws ClassCastException       {@inheritDoc}

      * @throws NullPointerException     {@inheritDoc}

      * @throws IllegalArgumentException {@inheritDoc}

      */

     SortedMap<K,V> tailMap(K fromKey);

 }